You're confusing two completely different things, market making and selling order flow. Market making doesn't require selling order flow and is absolutely essential to a functioning market. There are certainly entities acting as market makers on Korea and Hong Kong futures markets.
Payment for order flow (or identically directing order flow to your wholley owned sub), on the other hand, I find difficult to defend unless you're in a situation like Nadex with a new exchange and you need to demonstrate viability of the marketplace to attract third party MMs and reach critical mass in volume. My inclination is that we'd be almost universally better off without it absent those edge cases, although there may be some benefit to the overall market that I'm not aware of.